National Geographic's "Kingdom of the Oceans"

Inhabitants of the Sea

With three-fourths of our planet Earth underwater, a wild show is constantly playing out beneath the surface. In a four-hour, two-part special, Nat Geo WILD explorers the wonders of the inhabitants under the sea. "Kingdom of the Oceans" premieres on Sunday, March 10 and Sunday, March 17 at 8 and 9 p.m. ET/PT.

Inhabitants of the Sea

With three-fourths of our planet Earth underwater, a wild show is constantly playing out beneath the surface. In a four-hour, two-part special, Nat Geo WILD explorers the wonders of the inhabitants under the sea. "Kingdom of the Oceans" premieres on Sunday, March 10 and Sunday, March 17 at 8 and 9 p.m. ET/PT.

Inhabitants of the Sea

Shown here is a marine iguana. "The diversity of life in the oceans is staggering," Dr. Michael Hirshfield, a chief scientist with Oceana, told "Nightline." "There are whole groups of organisms that have no counterparts on land."

Galatée Films

Inhabitants of the Sea

The oceans are a world where life, put especially avoiding death, plays out against an often alien landscape. Here, birds nose dive beneath the surface of the waves off the coast of South Africa and into a large school of sardines, hoping to gobble up a quick meal.

Galatée Films

Inhabitants of the Sea

The eternal dance between the hunter and the hunted is, for all its brutality, balanced. Killer whales, shown here going after a seal, are one of the ocean's top predators.

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Inhabitants of the Sea

Creatures on the lower end of the food chain have developed astounding ways to protect themselves. The cuttlefish, for example, is a master of disguise, able to change the color of its skin to match its surroundings in seconds.

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Inhabitants of the Sea

The leafy seadragon's skin help give it the appearance of seaweed or kelp. It can also change color to blend in with its surroundings.

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Inhabitants of the Sea

Some, like this lion fish, also use their camouflage to ambush their prey. Lion fish have venomous spines, which can trap and kill other passing creatures.

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Inhabitants of the Sea

If camouflage isn't your thing, sometimes swimming next to something larger is the answer to avoiding predators. Here, a school a small fish is seen tailing a monstrous whale shark. "When you think about the open ocean, there are not a lot of places to hide so one of the best places to hide is near something big," Hirshfield said.

Galatée Films

Inhabitants of the Sea

Courtship and mating are another huge part of marine life. Once a year, spider crabs molt and mate in a massive orgiastic pile.

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Inhabitants of the Sea

"[For] millions of years, animals and plants evolved in the ocean and only relatively recently came out on land," Hirshfield said. "That's why there are so many different kinds of creatures in the ocean than there are on land." Sea turtles will crawl up on the beach, dig a hole and lay their eggs in the sand. When the eggs hatch, the babies have to make the long journey back to the ocean.

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Inhabitants of the Sea

A walrus and its calf rest on floating sea ice. So why should we care about the creatures of the deep and their future? Hirshfield said it is simply in our best interest. "Many economies are absolutely dependent on healthy oceans," he said, "The wonder and magic and beauty of the ocean are something that you should care about."

Galatée Films

Inhabitants of the Sea

A humpback whale leaps out of the water. "We're just beginning to understand how life works in the oceans," Hirshfield said. "We haven't even begin to scratch the surface."